Mold for the continuous casting of high-melting metals



Feb. 23, 1965 a. TARMANN 3,170,204

MOLD FOR THE commuous CASTING 0F HIGH-MELTING METALS Filed Feb. 20. 1961 r 3,170,204" MOLD non THE CONTINUOUS CASTING or HIGH-MELTING METALS Bruno Tarmann, Styria, Austria,-assignor to'Gebr. Biihler & Co. '-Aktiengesellschaft, Vienna, Austria Filed Feb. 20, 1961, Ser. No.'90,561 Claims priority, application Austria, FehJZS, 1960,

4 Claims. (31. 22 -136) v of adequate thermal conductivity, copper is a material suitable in the that placefor making the mold, and other materials will only be used when required for special reasons, leg, when the material cast in the mold is to be "subjected to electric induction.

In such cases, a lower If United States Patent 3,170,204 Patented Feb. 2 3, r 1965 I Surprisingly, however, it has'been found that the unde- I sired deformation in the neighborhood of the level of the thermal conductivity of the mold material must be accepted.

Regarding structure, there are integral and composite molds. The, composite molds are composed of plates whereas the integral molds consist of a prismatic or cylindnical tube. With respect to the cooling arrangement there are molds formed with cooling bores, and other surrounded by a water jacket. Regarding the wall thickness, there are thin-walled molds,..the wall thickness of which is only sufficient for the mechanical stresses to be expected which differ with the shape and sizeof the cross-section;

advantages of a thin-walled surface of thecast material can be avoided to a high degree if precipitation-hardened copper alloysare used which consist of more than 85% copper and at least one allo i velement which enables precipitation hardening.

It was not foreseeable that success could be obtained. in the present case by a measure which will necessarily reduce the thermal conductivity of copper.

Suitable alloying additions to the copper include mainly chromium, silicon, silver and beryllium. The amount of each of these materials should suitably not exceed 3%.

Such alloys known per se consist preferably of l-2% Cr, with or without O.ll% Si, balance copper and impurities which are inevitable in the manufacturing process.

It is essential for the invention that the alloys which are recommended and known per so are used in a precipitation-hardened condition becausoohly in this condition is the thermalconductivity not substantially less than that of pure copper whereas .=the'yields point at elevated temperature and the creep stress are much higher than the corresponding values for pure copper.

The precipitation-hardening treatment of these known alloys with, e.g.,' 1.5% Cr is effected by a solution annealing at about 1000 C. followed by quenching in water and reheating for one to four hours at temperatures between 350 and 600 0., preferably by reheatingfor two 7 hours at 400C. a

When welding operations are required during the manufacture of the mold, the precipitation-hardening treatment is suitably effected after the welding operation.

Molds according to the invention may consist partly or entirely of precipitation-hardened copper alloys.

Integral molds, which are in most cases subject to very lugh stresses, consist in condition ready for installation preferably entirely of a precipitation-hardened copper alloy owing to the simpler manufacture. a I

- On the other hand, it may be suitable in'the case 0 composite molds composed of plates to use the precipita tion-hardenable copper alloys onlyin the region where highstresses occur, mainly adjacent to the surface of the pouring rate andthe kind of steel to be poured; For

casting plants vary within a wide range. V I

The durability of a mold for continuous casting is essential for its usefulness. The durability may be expressed r this reason, the molds employed in existing continuous The high thermal" loading of the mold for continuous casting results in high stresses being set up in the mold wall as a result of thermal expansion, In continuous operati-on, these stresses result in deformation, which adversely affects the contact between the skin of the billet and the mold and consequently reduce the dissipation of heat.

- When the deformation has reached such :a degree that the formation of the skin is disturbed owing to anunsufiicient dissipation of heat, thebillet willshow surface cracks and the durability of the mold is exhausted.

It has now been observed that these undesired deforma- .rtions occur main-lyin the neighborhood of the level of the molten material. This levelnaries in the mold within a mange which can amount to :30 mm. evenyin a carefully controlled casting operation. It has also been observed that the molds are more liable to besubjected-to defiormation adjacent to the surfiace ofthe cast materialas desirable to provide a mold material havinga thermal conductivitywhich is higher than that of copper, if pos- .sible.' 1 r V the molten material. In that case the other parts of the mold consist of pure copper, as before. 1

The durability of molds for continuous casting according to the inventionis under comparable conditions in all previously observed cases a multiple of that of usual copper molds. 1

The subject matter of the invention will be described 7 i more in detail with reference to an illustrative embodiment. The drawing shows a mold for continuous casting. The mold 1 consisting of the alloy according to the invention is provided at both ends with flanges 2m 3, the

material of which need not consist of the alloy according to the invention but must be capable of being joined to the body of the mold without a gap." Besides, the mold 1s surrounded by a jacket 4, which serves to receive the cooling Water for cooling the wall of the mold and causing the solidification of the melt poured into the mold to the level L indicated by a broken line.

What is claimed is:

l. A mold forthe continuous casting of metals, said ,mold consisting of a precipitation hardened copper alloy at the level of molten material, said alloy consisting essentially of about 1% to2% chromium, incidential impurities and the balance being copperjand copper metal in the other level. V

2. A mold for the continuous casting of metals, said mold consisting of a precipitation hardened copper alloy at the level of molten material, said alloy consisting essent1al ly.of about 1% to 2% chromium, 0.1% to 1% silicon;

incidental impurities and the balance being copper; and

copper metal in the other level.

3. mold for the continuous casting of metals, said References Cited by the Examiner mold consisting of a precipitation hardened copper alloy UNITED STATES PATENTS at least at the level of molten material, said alloy consisting essentially of about 1% to 2% chromium, incidental 2'192497 3/40 Hessenbmch 75-.160 e 2,547,129 4/51 Klement 75153 XR impurities and the balance being copper. 4 5 n 4. A mold for the continuous casting of metals, said 2'944309 7/60 Schaaber 22-136 XR mold consisting of a precipitation hardened copper alloy at least at the level of molten material, said alloy consist- MICHAEL BRINDISI" Primary Examiner ing essentially of about 1% to 2% chromium, 0.1% to MARCUS U. LYONS, RAY K. WINDHAM, NEDWIN 1% silicon, incidental impurities and the balance 'being 10 BERGER, Examiners. copper. 

1. A MOLD FOR THE CONTINUOUS CASTING OF METALS, SAID MOLD CONSISTING OF A PRECIPITATION HARDENED COPPER ALLOY AT THE LEVEL OF MOLTEN MATERIAL, SAID ALLOY CONSISTING ESSENTIALLY OF ABOUT 1% TO 2% CHROMIUM, INCIDENTIAL IMPURITIES AND THE BALANCE BEING COPPER; AND COPPER METAL IN THE OTHER LEVEL. 